In 2006 alone, nearly 55,000 women either prior to or in their reproductive age range are expected to be diagnosed with cancer. For females undergoing radio- or chemotherapy for cancer treatment, iatrogenic damage to the ovaries is common, often resulting in infertility. Significant advances in treatment during the past few decades have improved the survival significantly among individuals diagnosed with cancer; the 5- year relative survival rate for all cancers diagnosed between 1995 and 2001 is 65%. It has been estimated that; by 2010, 1 in 250 people in the adult population will be cancer survivors. The remarkable success of improved cancer therapy has generated a significant societal need: namely, the development of effective means to preserve the fertility of individuals undergoing such therapies. Currently, all forms of female fertility preservation are considered experimental. Cryopreservation of cells and tissues is an interplay of as many as 8-12 factors, most of which interact. By establishing a clear understanding of the underlying fundamental cryobiological characteristics of the cells or tissues, we can develop mathematical models that enable us to design optimal methods. The overall goal of R01A under the auspices of the Oncofertility Consortium is to develop improved methods to cryopreserve primate oocvtes. immature follicles and ovarian tissue, based upon sound, fundamental crvobiological principles. We propose the following specific aims for this project: (1) develop and empirically test an optimized method for cryopreserving rhesus and human in vitro matured oocytes; (2): develop and empirically test an optimized method for cryopreserving rhesus and human immature follicles; (3): develop and empirically test an optimized method for cryopreserving rhesus and human ovarian cortical tissue. We are proposing a series of experiments to determine the tolerance of cells crucial for female fertility to several stresses associated with Cryopreservation including changes in temperature, osmolality, and cryoprotective agents. In addition, we are proposing experiments designed to understand biophysical characteristics of oocytes, follicles, and ovarian tissue, such as the permeability of the cells to cryoprotectants and the intracellular ice formation characteristics of whole ovarian tissue pieces. Used in conjunction with the tolerances of the cells to the stresses as described above, the resulting information will allow the development of theoretically-optimal Cryopreservation procedures. We will test these procedures using in vitro maturation, fertilization, and development as experimental endpoints. We will initially conduct all of the experiments using rhesus macaque oocytes, follicles and ovarian tissue. As new knowledge is gained from this approach and improved methods for Cryopreservation are developed, we will apply these developments to human oocytes, follicles and ovarian tissue working with the R01B in nonhuman primates, R01C human follicles and in conjuction with each of the training and social science programs (R01D, R25, T90/R90, K01).